Hiroshima: Ended WWII a year ahead of time and spared the lives of countless soldiers on both sides who would have died needlessly in a conventional invasion.
Chernobyl: A poorly designed nuclear reactor which completely failed when untrained technicians were ordered to perform a test on it. That could have happened if they were religious or not.
Asbestos: First used as early as 2500 BCE. It was only in the 20th Century that its harmful effects were discovered.
Thalidomide: Though it causes birth defects when taken by pregnant women, it is otherwise an effective treatment for leprosy, a horrible disease which certain holy books have claimed to be incurable except by the application of a miracle. The widespread use of the drug would not have caused the disaster that occurred if it had been properly tested before being released to the public.
Cane toads: Because, as we all know, there are no other invasive species that infested other landmasses before the 20th Century. You know, things like dingoes, rats, kudzu, and many others.
Global warming: Funny how the ultra-religious right are generally claiming that it doesn't exist and that, even if it did, it's perfectly acceptable since the world was created for humans to exploit in the first place.
The internet: Also an open forum for the free flow of information and exchange of ideas. All of the things mentioned (except lolcats) exist outside of the internet as well. Las Vegas. Bootleg tapes from as early as the 1960's. So on and so forth.
Wikipedia: This I have to agree with. Unless there is a more effective method of fact checking for this site, it will never be considered a valid source of information.